1. (noun)reason, ground a rationalmotive for a belief or action "the reason that war was declared"; "the grounds for their declaration"
2. (noun)reason an explanation of the cause of some phenomenon "the reason a steady state was never reached was that the back pressure built up too slowly"
3. (noun)reason, understanding, intellect the capacity for rationalthought or inference or discrimination "we are told that man is endowed with reason and capable of distinguishing good from evil"
4. (noun)rationality, reason, reasonableness the state of having goodsense and soundjudgment "his rationality may have been impaired"; "he had to rely less on reason than on rousing their emotions"
5. (noun)cause, reason, grounds a justification for something existing or happening "he had no cause to complain"; "they had good reason to rejoice"
6. (noun)reason a fact that logically justifies some premise or conclusion "there is reason to believe he is lying"
7. (verb)reason, reason out, conclude decide by reasoning; draw or come to a conclusion "We reasoned that it was cheaper to rent than to buy a house"
8. (verb)argue, reason present reasons and arguments
9. (verb)reason think logically
"The children must learn to reason"
Definition of 'reason':
